A lot of us get our interest from our parent/teachers/people around us sharing theirs, so why would Twilight or Luster be any different. Even if we don't pick it up on our own sometimes someone trying to introduce us to their interest can be just the start you need. So why couldn't Twilight get her totally-not-made-up-love of ninjas from Celestia (hey if you want to have some adventures and not get caught what better way then the art of stealth itself) or want to pass it on to her own student?
Ok, in all honesty I just wanted to draw Twilight and her student Luster Dawn from the finale of MLP (and Celestia). Though in this little ninja AU of mine I do consider Celestia the one that got Twilight into it, so yay for nonsensical AU building! As for the pic itself I think it came out great, though tall Twilight was a little odd at first but the more I look at it the better it works. I also had to do some debating about Luster's colors since she only gets a little screen time but these work, and it was nice to finally get to reveal Celestia's 'cause I've had them in mind for a long time.
I don't own these characters just the pic